The invention relates to an image processing apparatus and a process for exposing an intended image on an imaging drum or the like, and, more particularly, to an image processing apparatus incorporating a magnetic load roller, and a process for loading media in an image processing apparatus.
Pre-press color-proofing is a procedure that is used by the printing industry for creating representative images of printed material without the high cost and time that is required to actually produce printing plates and set up a high-speed, high volume, printing press to produce an example of an intended image. An image may require several corrections and be reproduced several times to satisfy or meet the customers requirements resulting in a large loss of profits and ultimately higher costs to the customer.
One such commercially available image processing apparatus is arranged to form an intended image on a sheet of thermal print media. Dye is transferred from a sheet of dye donor material to the thermal print media by applying a sufficient amount of thermal energy to the dye donor sheet material to form the intended image. This image processing apparatus generally includes a material supply assembly or carousel, and a lathe bed scanning subsystem or write engine, which includes a lathe bed scanning frame, translation drive, translation stage member, printhead, load roller, and imaging drum, and thermal print media and dye donor sheet material exit transports.
Operation of the image processing apparatus includes metering a length of the thermal print media (in roll form) from the material assembly or carousel. The thermal print media is then cut into sheet form of the required length and transported to the imaging drum. It is then registered, wrapped around, and secured onto the imaging drum. The load roller, which is also known as a squeegee roller, removes entrained air between the drum and the thermal print media. Next, a length of dye donor material (in roll form) is metered out of the material supply assembly or carousel, and cut into sheet form of the required length. It is then transported to the imaging drum and wrapped around it. A load roller is used to remove any air trapped between the imaging drum and the dye donor material. The dye donor material is superposed in the desired registration with respect to the thermal print media, which has already been secured to the imaging drum.
After the dye donor sheet material is secured to the periphery of the imaging drum, the scanning subsystem or write engine provides the scanning function. This is accomplished by retaining the thermal print media and the dye donor sheet material on the spinning imaging drum while it is rotated past the printhead to form an intended image on the thermal print media. The translation drive then traverses the printhead and translation stage member axially along the axis of the imaging drum in coordinated motion with the rotating imaging drum. These movements combine to produce the intended image on the thermal print media.
After the intended image has been formed on the thermal print media, the dye donor sheet material is removed from the imaging drum without disturbing the thermal print media beneath it. The dye donor sheet material is then transported out of the image processing apparatus. Additional dye donor sheet materials are sequentially superimposed with the thermal print media on the imaging drum, further producing an intended image. The completed image on the thermal print media is then unloaded from the imaging drum and transported to an external holding tray on the image processing apparatus.
Although the presently known and utilized image processing apparatus is satisfactory, a need exists to improve the load roller in regard to its interaction with the imaging drum, as well as mechanical adjustment and loading, and efficient removal of any air entrained beneath the print media.
Briefly summarized, according to one aspect of the present invention, the invention resides in an image processing apparatus comprising an imaging drum for holding a sheet of dye donor material and a sheet of thermal print media, and a magnetic load roller, which improves alignment, provides uniform loading to the imaging drum, and removes entrained air beneath the media. The image processing apparatus receives the thermal print media and the dye donor materials for processing an intended image onto the thermal print media. The magnetic load roller could in fact be utilized in any mechanical apparatus that requires a load roller.
According to a preferred embodiment of the present invention, an image processing apparatus for writing images to a thermal print media, comprises: a) a rotatable, magnet-attracting imaging drum mounted for rotation about an axis, the imaging drum being arranged to mount a receiver sheet and a donor sheet in superposed relationship thereon; b) a linear drive motor for rotating the imaging drum; c) a sheet transport assembly for transporting the thermal print media and donor sheets to the imaging drum; d) a printhead; e) a lead screw for moving the printhead in a first direction, the printhead being mounted on the lead screw; f) a linear translation subsystem on which the printhead, imaging drum, and lead screw are mounted; and g) a magnetic load roller.
Also included herein is an image producing process for loading thermal print media or donor material on an imaging drum, comprising the steps of:
a) rotating an imaging drum in a first direction of rotation;
b) actuating a sheet transport assembly and driving a sheet of thermal print media to the imaging drum until a leading edge of the thermal print media sheet engages the imaging drum, and then stopping the sheet transport assembly;
c) rotating the imaging drum in a second direction of rotation and stopping the imaging drum at a first media load position,
d) moving a magnetic load roller into engagement with the leading edge of the thermal print media sheet;
e) rotating the imaging drum in a second direction of rotation until a trailing edge of the thermal print media sheet is under the magnetic load roller, and then stopping rotation of the imaging drum; and
f) moving the magnetic load roller away from the imaging drum.
The present invention provides: a self-aligning, more reliable magnetic load roller that does not require a crown, and a magnet-attracting imaging drum. The magnetic load roller efficiently removes entrained air, therefore eliminating the need for a second pass with the load roller over the media. Also, the imaging drum preferably has at least one magnet embedded in its surface to aid in disengagement of the magnetic load roller from the imaging drum.